Earth boring bits are used in a number of different fields and applications, from drilling gas, oil, and water wells to various applications in the mining industry. One area in which earth boring drills are commonly used is in the formation of blasting holes for the insertion of explosives therein, for removing overburden in mining operations. This is particularly the case in open pit mining, where the loosened overburden is removed by means of dragline machines. Accordingly, one of the goals when blasting away the overburden is to throw or cast the material away from the mining face, where it can be more easily removed by the dragline process.
To accomplish the task of efficiently casting the overburden material away from the working face of the operation where it can be easily removed by the dragline bucket, the explosives set for blasting the overburden material away should be set or planted in a relatively precise pattern. This is achieved by drilling a series of blast holes into the overburden material, with the holes formed at an angle to the working face and converging toward an apex within the overburden material. The simultaneous detonation of explosives set within such a blast hole formation throws or casts the overburden material outwardly away from the working face of the operation where the cast away overburden material may be easily and efficiently removed by means of a dragline machine.
However, most earth boring drill bits are not optimally configured for drilling bore holes at an angle to the surface or to the rock or other hard strata beneath the surface. Most such bits have relatively shallowly inclined cutting faces, i.e., a large, obtuse included angle to the faces. This results in the outer edge or gauge portion of the bit making the first contact with the surface or stratum being drilled, with the result being the chattering or “walking” of the drill bit until it penetrates the surface or stratum. This is particularly hard on equipment, with the undue stress leading to damaged and broken bits, teeth, drill stems, and other equipment. This is not a small matter, as such earth boring bits can cost several thousand dollars to replace, and may require considerable labor to extract from a bore hole if the problem occurs in a stratum relatively deep within the hole.
Such earth boring drills conventionally remove the debris from the bore hole by applying a fluid (e.g., air) down the drill stem where it passes through the drill bit and blows or carries the loose material past the outside of the drill bit and stem out of the hole. Air is conventionally used for this purpose in mining operations, with the air being supplied by a compressor. It will be appreciated that the airflow at the drill head will be dependent upon the size and output of the compressor, as well as the internal diameter of the drill stem and passages through the drill bit or head. A compressor which is not capable of providing sufficient flow to create a relatively high velocity at the drill head cannot remove the loosened material from the bore hole, which may result in the jamming of the bit and stem in the hole. As in the problems noted above with broken bits and drill stems, the problems associated with inefficient removal of material from the bore hole can result in considerable expense and labor to correct.
Thus, an earth boring bit solving the aforementioned problems is desired.